Mammography - Still The Best Method for Breast Cancer Screening
By Dr. James Haroun, Director, Medical Imaging
The annual lifetime risk of a woman developing breast cancer is 1 in 8. This is an astonishingly high number, and it is no wonder that it invokes a large degree of apprehension for many women, particularly those who have a family history of breast cancer in a first degree relative, in which case the lifetime risk is even higher.
Now for some good news: The 5 year survival rate in recent studies for women diagnosed with breast cancer via screening mammography is actually 93 per cent. That's an astounding number of good outcomes. The bad news is that when breast cancer is diagnosed by other means (i.e. through a palpable "lump" by the patient or by the health care provider), the numbers are not so encouraging and are significantly worse, although I should mention that the vast majority of these women will still outlive their disease, particularly if the cancer is localized.
Another measure of how far we have come is that, over the past 35 years or so, 5 year survival rates for breast cancer have improved from 75% up to near 90 per cent, according to current studies. This progress has been attributed by experts to be a result of a combination of earlier diagnosis from better screening mammography programs, as well as significant improvements in treatment protocols. (By contradistinction, pancreatic cancer has a 5 year survival rate of approximately only 5 per cent, mostly due to its aggressive nature, and the fact that disease usually presents late and is often incurable, and is notoriously hard to image due to its deep location in the abdomen.)
When it comes to screening for breast cancer, mammography is still the method of choice. As I have written about in a previous article for this newsletter, digital mammography has several advantages over analog mammography, and we at Medcan use only state-of-the-art mammography in our screening protocols. We also use screening breast ultrasound for women with dense breasts.
With respect to mammography, we recommend a baseline mammogram between ages of 35 and 40, and yearly mammograms after age 40. The median age of breast cancer diagnosis is age 61. While it is true that only about 12 per cent of breast cancer occurs before age 45, the discouraging thing to note is that the types of breast cancers in the younger age groups tend to be more aggressive (presumably due to hormonal levels in pre-menopausal women and tumour response to these hormone levels). This is the reason we at Medcan subscribe to earliertreatment programs than Canadian provincial government standards often state (we at Medcan follow the American Cancer Society recommendations regarding yearly screening mammograms after age 40). I should point out that in my own practice I have diagnosed several women with breast cancer prior to age 50 on screening mammograms, so to me, the notion of not offering to screen younger women for this curable disease seems unfathomable.
The mammogram is a procedure that women don't generally like, and I can understand why. It can be stressful, and the compression needed to make an image can be very uncomfortable and as a result, tolerance of the procedure itself is quite variable. To explain why such machine compression is necessary is somewhat challenging in a short article, but in brief, the normal "overlapping" of the fibroglandular tissue of the breasts obscures visibility of malignancy for the radiologist. Proper compression attempts to separate "shadows" (overlapping tissue) to help improve the conspicuity of the potential malignancy, and is a necessary "evil". Our technologist Wanda Bennett does an excellent job in minimizing discomfort, but the nature of the test certainly does involve necessary compression. Understanding the reason for the compression can sometimes help with the pain tolerance, and in general 99% of women are able to tolerate the exam.
When a well-trained radiologist looks at a mammogram, generally a cancer (or other suspected abnormality) can often be differentiated from normal tissue by one of several ways. The varying appearance of breast cancer on mammography is usually grouped into masses, architectural distortion, asymmetries and suspicious micro calcifications. The diagnosis of breast cancer is predominantly made through pattern recognition. (I have interpreted more than 100,000 mammograms in my career. As a result, the interpretation of mammography has become second nature.).
The mammogram report is very basically broken down into three categories: "normal", a "definite malignancy", or a "can't tell/maybe" group. This third category is the trickiest, and usually involves further imaging (usually specialized mammography extra images, ultrasound or MRI) or even biopsy.
The "maybe" category is a tough one for both the radiologist and the patient. I should point out that over 95 per cent of the "maybe" category turns out to be benign tissue simulatinga cancer, so if you get recalled for further imaging, you should be advised that this is part of the screening process, and quite common. Most of the time, we can be reassured that there is no cancer by obtaining these extra views.
One way to cut down on the number of "maybe" recalls is to ensure you bring your previous mammograms with you at the time of your Medcan mammogram. If an abnormality that mimics cancer has been there for many years, it is generally a benign finding and we are reassured of its benign nature by comparing the old and the new study. This also helps the radiologist pick up subtle early cancers that weren't there before, so we strongly encourage providing previous mammograms whenever possible.
Another interesting point that women may not know is that in preparing for the mammogram we recommend that no deodorant be used prior to the study. The reason for this is that some deodorants contain a product that can actually mimic the micro calcifications seen in breast cancer.
In summary, breast cancer has a very high cure rate when diagnosed early (through screening mammography) and we strongly recommend following our screening protocol at Medcan of yearly digital mammograms after age 40.